Did you actually compare the features before buying it, or did you just assume a paid one would be better? I almost did the same thing last year with a VPN service, until a friend pointed out my browser already had a built-in one. These companies bank on people not checking what they already have.

I've noticed that same pattern with old diesel guys and starting fluid. They all swear by it when it's cold, but every single one has a story about that one time it went wrong and sounded like the engine was about to throw a rod through the block. It's like a rite of passage for anyone who works on these old beasts. You learn real quick that a little goes a long way, and too much turns your engine into a percussion instrument for a few terrifying seconds. The funny thing is, you see the same thing in other trades too, like mechanics who borrow someone else's tools and swear it's fine until a ratchet slips and costs them a knuckle. There's always that one lesson that sticks with you because it scared the daylights out of you.

Wait, isn't patching those old cloth shutters just asking for trouble later?

Yeah I had the same issue with T-molding for about four years. @lunab97 is right about getting in a rhythm and not noticing. What finally fixed it for me was marking the bottom track with a sharpie line so I'd know where to put the tape hook every time. The gap was always on the same side but I figured it was just the subfloor being uneven. Once I flipped the tape around it was night and day. Now I always double check which flange I'm referencing before I make any cut on transitions. Saves a lot of cussing and scrap pieces.

Those little angle errors add up faster than you'd think (in cranes and life).